Description

• An accumulation of fluid within the pericardium that causes compression of the chambers of the heart, impairing diastolic filling, reducing cardiac output, and ultimately leading to cardiovascular collapse
• Tamponade can be acute or subacute, depending on the etiology.
  • Acute: rapid accumulation (usually blood) within a stiff, noncompliant pericardium
  • Subacute: gradual increase of a preexisting effusion, overwhelming normal accommodative pericardial stretch

Epidemiology

Incidence
Difficult to assess due to absence of population-based studies

Prevalence
Difficult to assess due to absence of population-based studies

Etiology and Pathophysiology

• As a pericardial effusion accumulates, it overcomes the pericardium’s intrinsic compliance, yielding increased intrapericardial pressure. This pressure eventually exceeds intracardiac diastolic pressures, compressing the chambers of the heart and limiting diastolic filling, yielding a subsequent reduction of cardiac output.
• Diastolic filling is decreased first in the more compliant right-sided chambers—right atrium (RA), then right ventricle (RV)—followed by a decrease of the left ventricle (LV). Tamponade is defined as the critical point at which diastolic equalization of the LV and RV occurs, total venous return drops, and cardiac output falls.
• The hemodynamic significance of the effusion depends on the following:
  • Rate of accumulation
  • Compliance of the pericardium to accommodate the enlarging effusion
• Acute tamponade (typically from a rapidly accumulating hemopericardium, with as little as 50 to 100 mL of fluid)
  • Penetrating or blunt trauma (Up to 10% of blunt trauma results in cardiac tamponade.)
  • Iatrogenesis
    • Cardiac surgery
    • Pacer wire migration or electrophysiologic study
    • Central venous catheterization
    • Aortic dissection: rupture of cardiac free wall, ventricular aneurysm, or coronary artery; these most commonly occur during the post-myocardial infarction (MI) period.
• Subacute tamponade
  • Pericarditis (20% of subacute tamponade)
  • Iatrogenic effusions (16%) (see above)
  • Malignancy (13%): breast, lung, lymphoma, leukemia, or radiation pericarditis
  • Idiopathic effusion (9%)
  • Acute MI (8%)
  • End-stage renal disease (ESRD) (6%): usually BUN >60 mg/dL; hemodialysis is an independent risk factor.
  • Congestive heart failure (CHF) (5%)
  • Collagen vascular disease (5%): systemic lupus erythematosus, rheumatoid arthritis
  • Infection (4%)
    • HIV
    • Bacterial infection: Staphylococcus aureus, Mycobacterium tuberculosis, Streptococcus pneumoniae (rare)
    • Fungal infection: Histoplasma capsulatum
    • Viral infection: coxsackie group B, influenza, echoviruses (enteric cytopathogenic human orphan), herpes
  • Hypothyroidism with myxedema
  • Massive fluid resuscitation
  • Coagulopathies
• Low-pressure tamponade
  • Patients with preexisting effusions who receive hemodialysis or diuretics, thus, reducing intravascular volume
  • A decrease in intravascular volume can make an unchanged preexisting effusion hemodynamically significant.
• Regional tamponade (A loculation or hematoma limits diastolic filling.)
  • Loculations are often associated with tuberculosis.
  • Localized hematomas are associated with cardiac surgery or post-MI.
• Acute decompensation of a preexisting effusion
  • Influx of blood
  • Fragmentation of intrapericardial clots
  • Inflammatory stiffening of pericardium

Commonly Associated Conditions

Pericarditis